| Earliest Freeway Completed in L.A. County | Arroyo Seco Parkway (110) Completed: December 30, 1940 Length: 6 miles Cost: $5.7 million |
| Latest Freeway Project ENTIRELY in L.A. County | Glenn Anderson (Century) Freeway (105) Completed: October 14, 1993 Length: 17.3 miles Cost: $2.3 billion |
| Latest Freeway Project Completed in L.A. County | Foothill Freeway (210) Extension* Completed: November 24, 2002 Length: 6.5 miles (in L.A. County) Cost: $310 million (cost of portion in L.A. County) |
* The 210 extends into San Bernardino County. The total freeway extension was 14 miles and cost $689 million.
